Reaction Between Starch and Amylase
In this case the alternated factor is the concentration of amylase
which acts as an enzyme, affecting the rate of the reaction. (The
I aim to prove that -
SUBSTRATE ENZYME PRODUCT
Starch Amylase Sugar / glucose
Based on my preliminary results and my scientific knowledge I predict
that the higher the percentage of amylase
(the greater the
concentration) a speedier reaction of turning starch
lessening it's molecular size, similar to the reaction taking place
within the digestive system.
I am expectant that the test tube with the concentration of 100 %
amylase will be the fastest to react as amylase acts as an enzyme
which is a biological catalyst and there will be more particles of
amylase to collide with the starch, breaking the starch down faster.
The test tube containing no amylase and 100 % distilled water will
react the slowest and perhaps not at all because there will be no
particles of amylase to collide with the starch, which are there to
break the starch down faster.
Before conducting my actual experiment I ran a preliminary test to
base my prediction upon. This was basically to check that my
measurements were practical and I found that they were therefore; no
changing had to be made to my original measurements.
Factors that need to be controlled
As an independent variable, temperature will have an effect on the
rate of reaction and must be controlled, as the input variable to be
adapted is the concentration of amylase only, so during the experiment
the temperature is to be recorded.
To conduct both the preliminary and actual experiments I need the
* Spotting tile to place extracts of solutions
* Test tube rack to hold test tubes
* Test tubes (numerous or washed after each use to be sure of
conducting a fair experiment.)
* Amylase to be varied and acting as an enzyme on starch
* Double digit timer to time the rate of reaction
* Pipette to extract samples of the solutions
* Starch to be transformed into glucose
* Distilled Water (H20) to dilute amylase
* Iodine to present any signs of starch
* Measuring cylinders (10cm³)
Fair test awareness
When conducting an experiment where containers such as test tubes are
being used and filled with substances which, in this case is amylase,
the equipment used must be washed as any remaining liquid may have an
effect on the outcome variable therefore resulting in an unfair test.
I will be conducting the experiment twice then calculate an average
results for the fairest, most accurate results.
As always when experimenting within the science laboratory care must
be taken when handling equipment e.g. Only 1 or 2 objects to be
carried at all times, to be aware of others around you and to never
Also protective clothing such as goggles and lab coats must be worn
throughout the whole experiment.
To observe and vary the reaction between starch and amylase, firstly
protective clothing must be adorned then equipment assembled.
Starting with the highest concentration of amylase, Measure using the
cylinders, 100% Amylase (10 cm3) along with 4 cm3 of starch is placed
in a test tube, this is the point when the timer is started, then
stirred for 1 min then a 1ml extract is taken using a pipette and
placed on the spotting tile. Iodine is then added. This process of
extracting the solution of starch and amylase is then repeated until
either a distinct change of colour of the samples on the tile is
noticed and maintained or there has been no change in the sample
colour after the iodine has been added for some time, bearing in mind
how long some variation tests can take.
If sugar is shown to be gradually present the iodine and solution will
turn from a blue black (in the first samples showing signs of starch)
to a brown to an orange, signifying the presence of starch.
The equipment used is cleaned and the experiment is conducted again
using a different ratio of water to amylase. Next could be 4cm³ of
starch with 20% water and 80 % Amylase.
Enzymes and catalysts
Enzymes are proteins, which control the reactions occurring in our
Enzymes are also known as biological catalysts, which speed up a
reaction without taking part. The catalyst used in this experiment is
water. Catalysts lower the rate of the activation energy for a
reaction and so a reaction occurs faster. Therefore more enzymes
change starch into glucose.
Enzymes contribute to turning the substrate in products.
There are two kinds of amylase enzymes, One is Alpha amylase found in
saliva and can digest approximately 40 % of starch according to the
right conditions e.g. acidity of the stomach. The other kind is known
as pancreatic amylase.
Starch is very important for the existence of plants and animals and
is used commercially frequently.
The digestive systems in both plants and animals convert starch into
glucose for an energy source.
Starch can be detected by a blue-black colour when iodine is added to
Ratio of Water:
relative to undiluted
Amylase solution (%)
react (1) (s)
react (2) (s)
Rate of reaction
substrate to react)
The graph shows that the variable concentration of amylase solution
does affect the rate of the reaction between amylase and starch. The
line of best fit also backs up my prediction, in the relationship
between the rate of the reaction and the concentration of the amylase.
My line of best fit also supports my prediction. The points plotted
are close together and there is a positive correlation. There are no
anomalous results; this also shows that my results are accurate.
Analysis and Conclusion
Through my investigation, I have found, using my results that my
prediction: that the higher the concentration of amylase the faster
the starch will break down into glucose, was correct.
This is shown using the colour changes through the duration of the
experiment. Initially the extracts removed at the beginning of the
experiment, when added to iodine were black, indicating that starch
was still present, but as the time and the reaction between the
enzyme, amylase and the substrate starch, wore on, the samples when
added to iodine became lighter, through brown to a lighter brown to a
pale brown and finally to an orange colour, the same as iodine
signifying that no starch was present and it was now glucose.
When the concentration decreases there are less enzyme molecules to
break down the substrate at once. 1 amylase molecule can produce
100,000 molecules of glucose, per second, so if there are 2 molecules
they can produce 200,000 molecules of glucose. The number of
collisions per second is directly proportional to the number of active
sites, and this depends on the concentration of the enzyme, as the
higher the concentration, the more amylase molecules there are.
The more amylase molecules, the more enzymes there are to react with
and so the higher the chance of successful collisions between the
starch particles and the amylase particles.
If I were to conduct the experiment again I would try to be able to
keep the temperature as controllable as possible by making sure that
the experiment took place in an average room temperature by using a
My results would have been more accurate if I had done the experiment
more times, as this would have got a more accurate average result.
It may be also be able to explore my proven theory of the effect of
amylase on starch by using other enzymes such as lipase or protease.